The present invention relates to a shearing-stripping machine for electric cables.
It is well known that for shearing electric cables into sections of different length and stripping their ends and the possible wires constituting the cables, shearing-stripping machines are used, carrying out said operations starting from cables of indefinite length wound as a coil.
The working method generally provides for unwinding the cable from the coil and introducing it through suitable advancement devices into a shearing and stripping unit where the cable is firstly shorn to the desired length and then stripped at the ends.
When the cable comprises more wires, these wires may also be stripped for a determined stretch so as to uncover the conductors.
The above mentioned shearing-stripping machines of known type available on the market generally comprise one or more cable driving units and one or more shearing and stripping units, the latter being provided with opposite movable blades for shearing the cable and stripping its ends and possibly also the ends of each wire of the cable.
The shearing-stripping machines carrying out also stripping of the wires, in addition to the cable shearing and stripping unit, comprise also an alignment unit provided with opposite aligning jaws to place the wires juxtaposed to each other on an almost horizontal plane and opposite blades incising the sheaths and carrying out stripping of the wires after their alignment.
In such machines of the prior art the aligning jaws and the stripping blades are supported by suitable sliding units and are put in motion by suitable driving means moving them along a rectilinear direction generally orthogonal to the cable advancement direction.
In the above mentioned machines of the prior art, the stripping blades for the cable and the wires are juxtaposed on a generally vertical plane perpendicular to the cable advancement direction. Both blades are put in the working position by a first driving unit provided with an electric motor with electronic motion control, while a second driving unit also provided with electric motor with electronic motion control, move the blades in opposite directions to carry out incision and stripping.
Such machines, therefore, have the drawback of having high construction costs in view of the presence of two driving units each provided with a motor with electronic motion control and corresponding software.
Another drawback consists in that the presence of two motors involves greater difficulty of regulation and greater need of maintenance together with a lower reliability of operation.
A further drawback arises from the fact that the wire aligning jaws are independent from each other and each jaw is driven by a pneumatic actuator. Indeed, the independent pneumatic control on the jaws does not warrant the precise co-ordination of the movements of said jaws and consequently does not warrant that the wires are always aligned on the same generally horizontal plane. Consequently, during the wire stripping stage the blades could incise besides the sheaths also the conductors so as to damage the conductors and wear the blades.
The present invention aims at overcoming said drawback.
More particularly, a first object of the invention is to provide a shearing-stripping machine wherein the means for driving and controlling the movement of the stripping blades are of simpler construction in comparison of the known types.
Another object of the invention is to provide a shearing-stripping machine in which there is a unit for aligning the wires to be stripped having a self-centering effect on the wires so as to place them always aligned and coplanar during incision of the sheaths.
A further object of the invention is to provide a machine which is more reliable and less expensive to be constructed in comparison with the machines of the prior art.
Said objects are attained with a shearing-stripping machine for electric cables that according to the main claim comprises a casing on which the following elements are mounted: driving means to advance said cable to be shorn and stripped; at least a shearing and stripping unit comprising a blade guide body provided with first blades supported by first blade holders for shearing the cable, incising the sheath and stripping said cable and second blades for incising the sheaths of the wires of the cable and stripping said wires; at least an alignment unit of said wires adapted to place said wires juxtaposed and coplanar before incision of said sheaths by said second blades; first driving means for the movement of said first blades; second driving means for the movement of said second blades; at least a microprocessor unit controlling and actuating said driving means and said driving units, wherein said first driving means comprise a single motor coupled to a mechanism to which adjustable stop means for the stroke of said second blades are associated.
In this way with the same motor carrying out the movement of said first shearing and stripping blades, the control of the movement of the second stripping blades is obtained as well.
The motor is preferably an electric motor with electronic rotation control.
According to the preferred embodiment that will be described hereinafter, the mechanism comprises a screw coupled to the shaft of said single motor, said screw having opposite right-hand and left-hand threads coupled with corresponding screw nuts with which the adjustable stop means of the stroke of the second stripping blades are associated, which consist of the same first blade holders supporting the first shearing and stripping blades.
In this way the number of motors is advantageously reduced in comparison with those used to make equivalent machines of the prior art, to the advantage of a greater reliability of the machine and lower construction costs.